Endo-cavity focused ultrasound transducer

ABSTRACT

An apparatus for delivering acoustic energy to a target site adjacent a body passage includes first and second elongate members, each carrying one or more transducer elements on their distal ends. The first and/or second elongate members include connectors for securing the first and second elongate members together such that the transducer elements together define a transducer array. The first and second elongate members are introduced sequentially into a body passage until the transducer elements are disposed adjacent a target site. Acoustic energy is delivered from the transducer elements to the target site to treat tissue therein. In another embodiment, the apparatus includes a tubular member and an expandable structure carrying a plurality of transducer elements. The structure is expanded between a contracted configuration during delivery and an enlarged configuration when deployed for delivering acoustic energy to a target site adjacent the body passage.

RELATED APPLICATION DATA

This application is a continuation of U.S. application Ser. No.10/452,061, filed Jun. 2, 2003, which is hereby incorporated byreference in its entirely.

FIELD OF THE INVENTION

The present invention relates generally to apparatus and methods fordelivering acoustic energy, and more particularly to apparatus andmethods for delivering diagnostic and/or therapeutic ultrasonic energyfrom a transducer disposed within a body of a subject.

BACKGROUND

Devices and systems using acoustic energy, particularly within theultrasonic range (acoustic waves with a frequency greater than abouttwenty kilohertz (20 kHz), and more typically between fifty kiloHertzand five Megahertz (0.05-5 MHz)), have been used to diagnose and treatpatients. For example, ultrasonic energy may be employed to obtainimages of a region of a patient during a diagnostic or therapeuticprocedure. In addition, ultrasound systems have been used for treatingtissue, e.g., by focusing acoustic energy towards a target tissue regionwithin a patient, such as a cancerous or benign tumor, to necrose orotherwise heat the tissue region. For example, one or more piezoelectrictransducers may be disposed adjacent a patient's body and used todeliver high intensity acoustic waves, such as ultrasonic waves, to aninternal tissue region of a patient to treat the tissue region. Anexemplary focused ultrasound (“FUS”) system is disclosed in U.S. Pat.No. 4,865,042 issued to Umemura et al.

Focused ultrasound procedures may allow a patient to be treated withoutrequiring invasive surgery. Because ultrasonic transducers are generallydisposed adjacent to the patient, however, the acoustic path to a targettissue region may be at least partially obstructed, e.g., by anatomicalobjects such as bones or cavities, within the patient's body.Furthermore, acoustic energy may not be adequately focused at a locationdeep within a body, e.g., because the resulting focal zone may be toolarge to provide an effective and safe treatment. As such, it ispreferable to place the transducer as close to a target site aspossible.

To deliver acoustic energy to locations deep within the body, it hasbeen suggested to use natural body passages to place an acoustictransducer closer to a target site. For example, U.S. Pat. No. 5,666,954discloses a transducer that may be inserted into the rectal canalthrough the rectal orifice to treat prostate cancer. Natural bodypassages, however, may limit the size of the transducer that may beintroduced.

Generally, a relatively large transducer provides better control overthe size and intensity of the resulting focal zone. The size of atransducer that may be delivered inside a body passage may be limited bythe size of a body orifice at the entry point for the transducer. Forexample, the size of a transducer used for treating prostate cancer maybe limited by the maximum perimeter of the rectal orifice.

Accordingly, apparatus and methods for delivering acoustic energy withina patient's body would be useful.

SUMMARY OF THE INVENTION

The present invention is directed to apparatus, systems, and methods fordelivering diagnostic and/or therapeutic ultrasound energy to tissuewithin a subject. More particularly, the present invention is directedto apparatus and methods for delivering acoustic energy to targetregions within a patient using a transducer device introduced into abody passage of the patient.

In one embodiment, an apparatus for delivering acoustic energy mayinclude a first structure carrying a first transducer, and a secondstructure carrying a second transducer. The first and second transducersmay be disposable adjacent one another such that together they at leastpartially define a transducer array. In one embodiment, the firsttransducer may be configured to mate with the second transducer suchthat together they form at least a part of the transducer array. Forexample, a connector or other mechanism may be provided for securing thefirst structure to the second structure. The apparatus may include oneor more additional structures, each carrying a transducer that furtherdefines the transducer array. Each transducer of the apparatus mayinclude a single transducer element, although preferably, eachtransducer includes a plurality of transducer elements. In addition, theapparatus may include a balloon, bag, or other coupling membrane thatmay receive the first and second structures or otherwise may surroundthe resulting transducer array for acoustically coupling the transducerarray with surrounding tissue.

In accordance with another aspect of the present invention, an apparatusis provided for delivering acoustic energy that includes an expandablestructure carrying a plurality of transducer elements. The structure maybe movable into a contracted or low profile configuration to facilitateadvancing the structure into a body passage, and may be expandable to anenlarged configuration such that the plurality of transducer elementsdefine a transducer array Optionally, the apparatus may include atubular delivery device having a proximal end, a distal end, and a lumenextending between the proximal and distal ends. The structure may bedisposed within the lumen in the contracted configuration duringdelivery and may be expanded to the enlarged configuration when advancedfrom the lumen. The apparatus may also include a balloon, bag, or othercoupling membrane, similar to the previous embodiment.

In accordance with yet another aspect of the present invention, anapparatus is provided for delivering acoustic energy to a target siteadjacent a body passage that includes a first member including aproximal end, a distal having a size and shape for insertion into a bodypassage, and a first transducer carried on the distal end. The apparatusalso includes a second member also including a proximal end, a distalhaving a size and shape for insertion into the body passage, and asecond transducer carried on the distal end. The first and/or secondmembers include one or more connectors for substantially securing thefirst and second members relative to one another such that the first andsecond transducers together at least partially define a transducerarray.

In accordance with still another aspect of the present invention, amethod is provided for delivering acoustic energy into a target tissueregion adjacent a body passage. A first member is introduced into a bodypassage until a first transducer carried by the first member is disposedadjacent the target tissue region. A second member is introduced intothe body passage until a second transducer carried by the second memberis disposed adjacent the first transducer. Acoustic energy is deliveredfrom the first and second transducers towards the target tissue regionto treat tissue therein.

In accordance with yet another aspect of the present invention, anapparatus is provided for delivering acoustic energy to a target regionadjacent a body passage that includes a tubular member including aproximal end, a distal end having a size and shape for insertion into abody passage, and a lumen extending between the proximal and distalends, and a structure carrying a plurality of transducer elements, thestructure being movable between a contracted configuration when disposedwithin the lumen of the tubular member, and an enlarged configurationwhen deployed from the lumen such that the plurality of transducerelements at least partially define a transducer array for deliveringacoustic energy to a target region adjacent the body passage.

In accordance with still another aspect of the present invention, amethod is provided for delivering acoustic energy into a target tissueregion adjacent a body passage. An expandable structure is introducedinto a body passage while in a contracted configuration, the expandablestructure carrying a plurality of transducer elements. The expandablestructure is expanded towards an enlarged configuration, therebyarranging the plurality of transducer elements into an array. Acousticenergy is delivered from the plurality of transducer elements towardsthe target tissue region.

Other aspects and features of the invention will be evident from readingthe following detailed description of the preferred embodiments, whichare intended to illustrate, not limit, the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of preferred embodimentsof the present invention, in which similar elements are referred to bycommon reference numerals. In order to better appreciate how advantagesand objects of the present inventions are obtained, a more particulardescription of the present invention briefly described above will berendered by reference to specific embodiments thereof, which areillustrated in the accompanying drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered limiting its scope, the invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings.

FIG. 1 shows an exemplary ultrasound system including a transducerdevice delivering acoustic energy to a target tissue region within apatient.

FIG. 2 is a perspective view of a first preferred embodiment of atransducer device, including first and second elongate members carryingtransducer elements, that may be used in the system of FIG. 1.

FIG. 3 is a perspective view of the transducer device of FIG. 2, showingthe first and second elongate members mated together such that thetransducer elements define a transducer array.

FIG. 4 is a cross-sectional side view of an alternative embodiment ofthe transducer device of FIGS. 2 and 3, including an expandable balloonsurrounding the transducer elements.

FIG. 5 is a perspective view of the transducer device of FIG. 4, showinga plug for sealing an inlet of the balloon and a source of inflationfluid coupled to the plug.

FIGS. 6 and 7 are perspective views of another embodiment of atransducer device, including an expandable structure carrying aplurality of transducer elements in enlarged and contractedconfigurations, respectively.

FIG. 8 is a cross-sectional side view of the transducer device of FIGS.6 and 7, including an expandable balloon surrounding the expandablestructure.

FIGS. 9A-9C are cross-sectional views of a body passage, showing amethod for treating tissue adjacent the body passage using a transducerdevice introduced into the body passage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning to the drawings, FIG. 1 shows an exemplary embodiment of afocused ultrasound system 5 including a transducer device 10, drivecircuitry 16 coupled to the transducer device 10, and a controller 18coupled to the drive circuitry 16. As shown, the transducer device 10generally may be introduced into a body passage 92 within a patient 90and used to deliver acoustic energy (represented by beam 15) to a targettissue region 94 located adjacent the body passage 92. The acousticenergy 15 may be used to necrose, heat, or otherwise treat the targettissue region 94, which may be a benign or malignant tumor within anorgan or other tissue structure (not shown).

The transducer device 10 generally includes one or more transducers 12that are coupled to the driver 16 and/or controller 18 for generatingand/or controlling the acoustic energy emitted by the transducer 12. Forexample, the driver 16 may generate one or more electronic drivesignals, which may be controlled by the controller 18. The transducer 12converts the drive signals into acoustic energy 15, which may be focusedusing conventional methods.

The controller 18 and/or driver 16 may be separate or integralcomponents. It will be appreciated by one skilled in the art that theoperations performed by the controller 18 and/or driver 16 may beperformed by one or more controllers, processors, and/or otherelectronic components, including software and/or hardware components.The terms controller and control circuitry may be used hereininterchangeably, and the terms driver and drive circuitry may be usedherein interchangeably.

The driver 16, which may be an electric oscillator, may generate drivesignals in the ultrasound frequency spectrum, e.g., as low as twentykilohertz (20 kHz), and typically ranging from about half to tenMegahertz (0.5 to 10 MHz). Preferably, the driver 16 provides drivesignals to the transducer 12 at radio frequencies (RF), for example,between about half to ten Megahertz (0.5-10 MHz), and more preferablybetween about one and two Megahertz (1.5 and 2.5 MHz). When the drivesignals are provided to the transducer 12, the transducer 12 emitsacoustic energy 15 from its exposed surface, as is well known to thoseskilled in the art.

The controller 18 may control the amplitude, and therefore the intensityor power of the acoustic waves transmitted by the transducer 12. Thecontroller 18 may also control a phase component of the drive signals torespective transducer elements of the transducer 12, e.g., to control ashape of a focal zone 38 generated by the transducer 12 and/or to movethe focal zone 38 to a desired location. For example, the controller 18may control the phase shift of the drive signals based upon a radialposition of respective transducer elements of the transducer 12, e.g.,to adjust a focal distance of the focal plane (i.e., the distance fromthe face of the transducer 12 to the center of the focal zone). Inaddition or alternatively, the controller 18 may control the phase shiftof the drive signals based upon a angular position around the face ofthe transducer device, e.g., to adjust a shape of the focal zone, as iswell known to those skilled in the art. In addition or alternatively,the transducer 12 may be pivotable and the controller 18 may control oneor more tilt angles of the transducer 12.

As explained above, the transducer 12 converts the drive signals intoacoustic energy represented by energy beam 15. As the acoustic energy 15passes through the patient's body, the acoustic energy 15 is convertedto heat at the focal zone within target region 94, thereby raising thetemperature of tissue within the target region 94. The acoustic energy15 may be focused on the target region 94 to raise the temperature ofthe tissue to necrose the tissue within the target region 94 whileminimizing damage to surrounding healthy tissue. Exemplary apparatus formeasuring and/or calibrating the energy output of a transducer deviceare described in U.S. patent application Ser. No. 10/005,845, filed Dec.3, 2001. The disclosure of this application and any references citedtherein are expressly incorporated herein by reference.

Turning to FIG. 2, a first embodiment of a transducer device 100 isshown that includes a first structure or elongate member 102 and asecond structure or elongate member 104. The first elongate member 102includes a proximal end 106, a distal end 108, and one or moretransducer elements 110 carried on the distal end 108. The secondelongate member 104 also includes a proximal end 112, a distal end 114,and one or more transducer elements 116 carried on the distal end 114.The first and second elongate members 102, 104 may be substantiallyrigid, semi-rigid, or substantially flexible, preferably havingsufficient column strength such that the distal ends 108, 114 may beadvanced into a body passage from the proximal ends 106, 112 withoutsubstantially buckling or kinking.

As shown in FIG. 3, the first and second elongate members 102, 104 maybe mated together such that the transducer elements 110, 116 togetherprovide a transducer array 118. Preferably, the first and secondelongate members 102, 104 include cooperating connectors that mayremovably secure them together. For example, a hook or tab 120 may beprovided on the first elongate member 102 that may be received in acorresponding opening or slot 122 (shown in phantom) in the secondelongate member 104, as shown in FIG. 2. Alternatively, other connectorsor locking mechanisms may be provided, as will be appreciated by thoseskilled in the art. For example, a snap-fit or compression-fitmechanism, cooperating slots and/or tabs for sliding engagement, and thelike (not shown) may be provided for detachably securing the first andthe second elongate members 102, 104 to one another.

Each of the elongate members 102, 104 has a cross-sectional dimension orwidth that allows the distal ends 108, 114 to be inserted into a bodypassage (not shown). The body passage may be a natural passage, such asa rectal orifice, mouth, esophagus, a nasal orifice, vagina, bloodvessel, and the like. Alternatively, the body passage may be asurgically-created passage, e.g., as created using an endoscopic orlaparoscopic instrument (not shown). As such, the cross-sectionaldimension of each of the elongate members 102, 104 may vary dependingupon the particular application or surgical procedure. Generally, theelongate members 102, 104 may be inserted through an initial, relativelynarrow orifice into a body passage or cavity having a larger size. Thus,the initial orifice may be the limiting factor dictating the maximumcross-sectional dimension or width of the individual elongate members.

In one embodiment, the distal end 108, 116 of each of the elongatemembers 102, 104 has a cross-sectional dimension that is sufficientlysmall to allow the respective distal end 108, 114 to be insertedindividually through a rectal orifice (not shown). Once inserted throughthe rectal orifice, the rectum or colon may provide greater space, e.g.,such that the distal ends 108, 114 may be assembled together. In thisexample, the width or cross-sectional dimension for the distal ends 108,116 may be between about ten and seventy millimeters (10-70 mm).

In a preferred embodiment, the elongate members 102, 104 aresubstantially symmetrical and have similar widths, as shown in FIGS. 2and 3. In alternative embodiments, the elongate members 102, 104 mayhave different dimensions and/or may be asymmetrical relative to eachother. In further alternatives, one or more additional elongate members(not shown) may be provided that include one or more transducer elementssuch that the transducer device may include three or more elongatemembers (not shown). Thus, the first and second members may be dividedinto two or more additional elongate members, depending upon the desiredmaximum cross-section of each individual elongate member, i.e.,depending upon the relative size of the assembled transducer array andthe orifice through which the components must pass into the body.

The elongate members 102, 104 may be made from a variety of materials,such as plastics, polymers, metals, and alloys. In the illustratedembodiment, each of the elongate members 102, 104 has an elongated body.However, the elongate members 102, 104 may have other shapes and formsso long as they are capable of providing a platform or area for carryingthe respective transducer elements 110, 116.

Each of the transducer elements 110, 116 may be a one-piece piezoceramicelement, or alternatively, a mosaic arrangement including a plurality ofsmall piezoceramic elements. The piezoceramic element(s) may have avariety of geometric shapes, such as hexagons, triangles, squares, andthe like, and may be disposed about a central axis 119 of the elongatemembers 102, 104. In a preferred embodiment, the central axis 119 may belocated on the distal ends 108, 114 at a junction between the first andsecond elongate members 102, 104. More preferably, the transducerelements 110, 116 are arranged on the distal ends 108, 114 in asubstantially uniform or symmetrical configuration about the centralaxis 119.

In addition, the elongate members 102, 104 may include one or moreleads, e.g., wires or conductive paths (not shown), extending betweenthe proximal ends 106, 112 and distal ends 108, 114, and coupled to thetransducer elements 110, 116. The proximal ends 106, 112 may includeconnectors (not shown) for connecting cables and the like to theelongate members 102, 104, e.g., to couple the transducer elements 110,116 to a driver 16 and/or controller 18 (not shown, see FIG. 1). Thus,the driver 16 and/or controller 18 may generate drive signals forcausing the transducer elements 110 and 114 to emit acoustic energy. Inan alternative embodiment, each of the elongate members 102, 104 may becoupled to a separate driver (not shown) that is connected to a commonor separate controller(s). In yet another alternative embodiment, one ofthe elongate members 102, 104 may be coupled to a driver, and the otherof the elongate member 102, 104 may be coupled to leads in the firstelongate member when the elongate members 102, 104 are connected to oneanother.

As shown in FIG. 3, once the transducer device 100 is assembled, thetransducer elements 110, 116 define an assembled transducer array 118.The transducer array 118 may have a variety of shapes andconfigurations. In one embodiment, the transducer array 118 may have aconcave or bowl shape, such as a “spherical cap” shape, i.e., having asubstantially constant radius of curvature such that the transducerarray 118 has an inside surface defining a portion of a sphere.

Alternatively, the transducer array 118 may have a substantially flatconfiguration (not shown), and/or may include an outer perimeter that isgenerally, but not necessarily, circular (not shown). The transducerarray 118 may be divided into any desired number of rings and/or sectors(not shown). In one embodiment, the transducer array 118 may have anouter diameter of between about thirty and seventy millimeters (30-70mm), a radius of curvature between about thirty and fifty millimeters(30-50 mm), and may include between about forty and five hundredelements. For example, the transducer array 118 may be divided intobetween about ten and thirty (10-30) rings and about four and sixteen(4-16) sectors, although the transducer array 118 is not limited to sucha configuration.

The assembled transducer array 118 may also have other configurations,such as flat circular arrays, linear arrays, and the like, so long as itmay be detachably assembled from the transducer elements 110, 114carried by multiple structures, such as the elongate members 102, 104.The transducer array 118 may be arranged generally in a plane that issubstantially parallel to the longitudinal axis 103 of the elongatemembers 102, 104, or the array 1118 may be oriented at an angle withrespect to the longitudinal axis 103. Additional information on theconstruction and use of transducer arrays may be found in co-pendingapplication Ser. No. 09/884,206, filed Jun. 19, 2000. The disclosure ofthis application and any references cited therein are expresslyincorporated herein by reference.

Referring to FIG. 4, the transducer device 10 may also include acoupling membrane, such as an inflatable bag or balloon 150. The balloon150 includes a proximal end 152, a distal end 154, and an interior 156within which the first and/or second elongate members 102, 104 may bedisposed. The proximal end 152 of the balloon 150 has an opening 157communicating with the interior 156 for delivering fluid therein. Theballoon 150 may be expandable from a collapsed configuration tofacilitate insertion into a body passage to an expanded configurationfor substantially engaging tissue surrounding the body passage whenfluid 158 is introduced into the interior 156. The balloon 150 may besubstantially inelastic, i.e., may be folded or otherwise compressedinto the collapsed configuration, and may be expanded to a predeterminedsize as fluid is introduced into the interior 156. Alternatively, theballoon 150 may be elastic and/or compliant such that the balloon 150may expand to fill the available volume and may substantially conform tothe shape of the wall and tissue surrounding the body passage.

The fluid 158 may be a liquid acoustic propagation medium forpropagating or transmitting acoustic energy generated by the transducerarray 118. The balloon 150 and/or fluid 158 preferably have an acousticimpedance that corresponds substantially to the acoustic impedance oftissue. For example, the balloon 150 may be made from a polymer orrubber, such as EPDM rubber, and the fluid 158 may be degassed water.

As shown in FIG. 5, the transducer device 100 may include a coupler orplug 170 that may be received in the opening 157 or otherwise secured tothe proximal end 152 of the balloon 150. The plug 170 may include anadapter (not shown) for coupling the proximal end 152 of the balloon 150to a source of fluid 171. In the illustrated embodiment, the plug 170 isan annular body including an opening 172 through which the proximal ends106, 112 of the elongate members 102, 104 may be received. The plug 170,as shown, has a circular cross-sectional shape, although the plug 170may have other cross-sectional shapes, such as an elliptical shape, arectangle shape, or other desired shapes. The plug 170 preferably has ashape for mating with the proximal end 152 of the balloon 150, or theplug 170 and/or proximal end 152 may include connector(s) for securingthe plug 170 to the balloon 150.

The plug 170 may include a port 174 extending therethrough fordelivering and/or draining fluid 158 within the balloon 150.Alternatively, the plug 170 may include a separate inlet port (notshown) for delivering fluid 158 to the interior 156 of the balloon 150,and an outlet port (also not shown) for draining fluid 158 from theinterior 156 of the balloon 150. Thus, delivery tube(s) (not shown) maybe connected to the port(s) that may be connected to a source of fluidor a source of vacuum, e.g., a syringe and the like (not shown).

Turning to FIGS. 9A-9C, the transducer device 10 may be used to treat atarget tissue region adjacent to a body passage. For example, the targettissue region may be a region 94 within a prostate 96, and the bodypassage may be a rectum or colon 92. As explained above, the transducerdevice 10 may be used to treat other target tissue regions, such asbenign or malignant tumors, within organs or other tissue structures,that is located adjacent a body passage, which may be a natural passageor one surgically-created to provide access.

First, as shown in FIG. 9A, if the transducer device 10 includes aballoon 150, the balloon 150 may be inserted into the rectum 92 throughrectal orifice 98. Initially, the balloon 150 may be provided in acollapsed condition, e.g., disposed within a lumen of a tubular deliverydevice (not shown), and advanced into the rectum 92 through the rectalorifice 98. For example, a distal end of the tubular device may beinserted first into the rectum 92, and then the balloon 150 may beinserted through the lumen of the tubular device. In addition oralternatively, the balloon 150 may be carried on an introducer that maybe inserted through the proximal end 152 into the interior 156 of theballoon 150 before the balloon 150 is inserted through into the rectum92. The balloon 150 may be collapsed around the introducer and thenadvanced into the lumen of the tubular device. Alternatively, theballoon 150 carried on the introducer may be inserted directly into therectum without the tubular device. In a further alternative, the balloon150 may be sufficiently rigid that it may be advanced through the lumenof the delivery device without an introducer. The delivery device and/orintroducer may be removed from the rectum 92 once the balloon 150 ispositioned adjacent the target tissue region 94. To facilitate theirremoval, fluid may be introduced into the interior 156 of the balloon150 to separate the balloon 150 from the introducer.

Next, as shown in FIG. 9B, the distal end 108 of the first elongatemember 102 may be inserted through the rectal orifice 98 into the rectum92, preferably through the proximal opening 152 in the balloon 150 suchthat the distal end 108 enters the interior 156 of the balloon 150.Because of the width of the distal end 108, the rectal orifice 98 may bepartially dilated to facilitate its insertion. However, because thedistal end 108 is substantially smaller than the overall size of theassembled transducer array 118 (see FIG. 9D), risk of damaging therectal orifice 98 is substantially reduced during insertion of the firststructure 102.

Similarly, as shown in FIG. 9C, the distal end 114 of the secondelongate member 104 may be inserted through the rectal orifice 98 intothe rectum 92, e.g., into the interior 156 of the balloon 150. Theproximal end 106 of the first elongate member 102 already occupies aportion of the rectal orifice 98, and so the distal end 114 of thesecond elongate member 104 must be introduced adjacent to the firstelongate member 102. The relative configuration, e.g., widths orcross-sectional dimensions, of the distal ends 108, 114 may be sized todictate the order in which the elongate members 102, 104 are insertedinto the rectum 92, as will be appreciated by those skilled in the art.Generally, because the distal end 114 of the second elongate member 104also has a cross-section sufficiently small to allow insertion of thedistal end 114 through a rectal orifice 98, injury to the rectal orifice98 is substantially reduced.

Turning to FIG. 9D, once the distal ends 108, 114 have been insertedinto the rectum 92, the distal ends 108, 114 and/or the balloon 150 maybe positioned to orient the transducer elements 110, 116 relative to thetarget region 94. In an alternative embodiment, the balloon 150 may beprovided around the distal end 108 of the first elongate member 102initially collapsed, and introduced simultaneously with the firstelongate member 102.

The first and second elongate members 102, 104 may be secured together,e.g., using the cooperating hook 120 and slot 122 (not shown, see FIG.2), to ensure that the transducer elements 110, 116 are arrangedadjacent to one another to define the assembled transducer array 118.Alternatively, the first elongate member 102 may include an elongatetrack or rail (not shown) along which the second elongate member 104 maybe advanced when inserted into the rectum 92 to dispose the transducerelement(s) 116 adjacent the transducer element(s) 110. Thus, theresulting transducer array 118 may have an overall cross-sectionaldimension that may be maximized relative to the narrow rectal orifice98, i.e., that exceeds the size of single-piece transducer array thatmay be inserted through the rectal orifice 98. In a further alternative,the elongate members 102, 104 may remain free from one another, i.e.,not connected, while the transducer elements 110, 116 may disposedadjacent one another. In this embodiment, one or both elongate members102, 104 may carry a tracking device for monitoring their locationrelative to one another and/or the target tissue region 94.

If the transducer device 10 includes the balloon 150, the plug 170 (notshown, see FIG. 5) may be connected to the proximal end 152 of theballoon 150, and a source of fluid 171 (also not shown, see FIG. 5) maybe coupled to the plug 170 for delivering fluid into the balloon 150.The plug 170 may be advanced over the proximal ends 106, 112 of theelongate members 102, 104, i.e., with the proximal ends 106, 112 passingthrough the opening 172. The plug 170 may slidably and sealingly engagethe elongate members 102, 104 to prevent substantial leakage of fluidthrough the opening 172. Optionally, the plug 170 may sufficientlystabilize the distal ends 108, 114 of the elongate members 102, 104 thatno other connectors or locking mechanism may be necessary.

As shown in FIG. 9D, fluid may be introduced into the interior 156 ofthe balloon 150 to expand the balloon 150 until it substantially engagesthe wall of the rectum 92. Preferably, the balloon 150 substantiallyconforms to the shape of the wall of the rectum 92 to minimize gaps andenhance acoustically coupling the transducer array 118 to tissuesurrounding the rectum 92. After a desired amount of fluid has beendelivered, the port 174 of the plug 170 (not shown) may be closed toprevent fluid from escaping from the interior 156 of the balloon 150.Alternatively, if the transducer device 10 does not include the plug170, tubing (not shown) may be inserted into the proximal end 152 of theballoon 150 that is coupled to a source of fluid for inflating theballoon 150, whereupon the proximal end 152 of the balloon 150 may besealed, e.g., using a clip, cap, and the like (not shown).

The transducer array 118 may be oriented towards the target tissueregion 94, i.e., within the prostate 96, which may require the proximalends 106, 112 of the elongate members 102, 104 to be positioned ormanipulated further. Positioning the transducer array 118 may bemonitored using imaging techniques known in the art, such as fluoroscopyand ultrasonic imaging. Radiopaque markers (not shown) may be providedon one or both of the distal ends 108, 114 of the elongate members 102,104 to assist monitoring and positioning the transducer array 118.

Once the transducer 118 is properly oriented, the transducer array 118is then activated to deliver acoustic energy to the target tissue region94. The driver 16 and/or controller 18 (not shown, see FIG. 1) maycontrol the acoustic energy emitted by the transducer array 118 to focusand/or adjust the intensity of the acoustic energy to heat the targettissue region 94, while minimizing heating tissue surrounding the targettissue region 94. The fluid-filled balloon 150 may enhance acousticcoupling of the transducer array 118 with the intervening tissue betweenthe rectum 92 and the target tissue region 94, as explained above.

If the first and second elongate members 102, 104 are not connected toone another, they may be manipulated individually or together. Inaddition, each transducer element 110, 116 may be tested, e.g.,activated individually using relatively low power, to confirm that eachtransducer element 110, 116 is oriented towards the target tissue region94 before activating the entire transducer array to treat the targettissue region 94. If the focal zone of each transducer element 110, 116is not properly focused at the target tissue region 94, the focal zonemay be adjusted physically and/or electronically, as will be appreciatedby those skilled in the art. Thus, the transducer elements may beprovided at different positions and/or angles relative to one anotherbefore the transducer array is activated to treat the target tissueregion 94. In further alternatives, transducers may be introduced intodifferent body passages and positioned and/or focused towards a targettissue region adjacent to each of the transducers.

After a desired amount of acoustic energy has been delivered, e.g., toablate or otherwise treat the target tissue region 94, optionally, thetransducer device 10 may be moved to another location, electronicallysteered, and/or otherwise repositioned within the rectum 92, e.g., withthe elongate members 102, 104 and/or balloon 150 remaining assembledtogether. Additional tissue regions may then be treated. Alternativelyor finally, the transducer device 10 may be removed from the rectum 92via the rectal orifice 98. Generally, this involves deflating theballoon 150, disconnecting the elongate members 102, 104 (if securedtogether), and removing the elongate members 102, 104 one at a time. Theballoon 150 may be removed with the final elongate member or after allof the elongate members are removed from the rectum 92.

Turning to FIGS. 6-8, another embodiment of a transducer device 200 isshown that includes a tubular delivery device 202, and an elongatemember 220 carrying a plurality of transducer elements 206. The tubulardelivery device 202 has a proximal end 210, a distal end 212, and alumen 214 extending between the proximal and distal ends 210, 212. Theelongate member 220 includes a proximal end 222, a distal end 223, andan expandable structure 224 on the distal end 223 that carries thetransducer elements 206. Optionally, the transducer device 200 may alsoinclude a balloon, bag, or other coupling membrane 251 (shown in FIG. 8)and a coupler or plug (not shown) for sealing the balloon 251 and/orcoupling a source of fluid to the balloon 251 medium, similar to theembodiments described previously with reference to FIGS. 4 and 5

The expandable structure 224 may be bent, folded, or otherwise collapsedinto a low profile or contracted configuration (shown in FIG. 7), e.g.,to facilitate advancing or retracting the expandable structure 224 outof and into the lumen 214 of the delivery device 202. The structure 224is also expandable to an enlarged configured (shown in FIG. 6) forarranging the transducer elements 206 to define a transducer array 220.The elongate member 222 may be a substantially rigid, semi-rigid, orflexible wire or other body and the expandable structure 224 may beattached to or otherwise carried by the distal end 223.

The expandable structure 234 may be made from an elastic material, suchas plastic and/or metal, e.g., biased to expand towards the enlargedconfiguration, yet elastically deformable towards the contractedconfiguration. In a preferred embodiment, the expandable structure 224may be formed from a super-elastic alloys, such as a nickel/titanium(“Nitinol”) alloy. Other materials known in the art may also be used solong as the expandable structure 224 is capable of performing thefunctions described herein.

The expandable structure 224, elongate member 220, and/or deliverydevice 202 may include one or more radiopaque markers (not shown) toassisting monitoring the transducer device 200 as it being manipulatedwithin a body passage of a patient. For example, the expandablestructure 224 may be coated or mixed with radiopaque materials, such astantalum, gold, tungsten or platinum, barium sulfate, bismuth oxide,bismuth subcarbonate, and the like. Alternatively, continuous ordiscrete radiopaque markers may be affixed to the expandable structure224. In a further alternative, one or more of the components may includemicro-coil trackers that may be compatible for monitoring using MRI.

In the exemplary embodiment shown in FIGS. 6 and 7, the expandablestructure 224 may include a plurality of petals 225, each carrying oneor more transducer elements 206. The petals 225 may be connected to thedistal end 223 of the elongate member 220 by respective hinged regions,which may be living hinges, pinned hinges, and the like. The petals 224may be biased to assume the enlarged configuration automatically whendeployed from the lumen 214 of the delivery device 202, but may becompressed into the contracted configuration simply by retracting thedistal end 223 of the elongate member 220 into the lumen 214.Alternatively, the petals 225 may be coupled to wires or other elements(not shown) that may be manipulated to expand and/or contract the petals 225. The number of petals 224 may vary, e.g., four, five, six (asshown), or more, and should not limited to the illustrated embodiment.

Each of the transducer elements 206 may include a single piezoceramicelement or preferably may include a mosaic arrangement including aplurality of small piezoceramic elements. The piezoceramic elements mayhave a variety of geometric shapes, such as hexagons, triangles,squares, and the like.

Similar to the previous embodiments, a driver 16 and/or driver 18 (notshown, see FIG. 1) may be coupled to the transducer elements 206, e.g.,by leads (not shown) on or in the elongate member 220. The transducerelements 206 may be driven with respective drive signals for focusingacoustic energy transmitted by the transducer elements 206 towards afocal zone within a target region. Phase, amplitude, and/or otherparameters of the drive signals may be controlled to provide a desiredsize, shape, and/or location for the focal zone, similar to the previousembodiment.

In the enlarged configuration shown in FIG. 6, the resulting transducerarray 226 may have a variety of shapes and configurations. In oneembodiment, the transducer array 226 may have a concave or bowl shape,such as a “spherical cap” shape, i.e., having a substantially constantradius of curvature such that the transducer array 226 has an insidesurface defining a portion of a sphere. Alternatively, the transducerarray 226 may have a substantially flat configuration (not shown),and/or may include an outer perimeter that is generally, but notnecessarily, circular (not shown). The transducer array 226 may bedivided into any desired number of rings and/or sectors (not shown), allsimilar to the previous embodiment.

Those skilled in the art will appreciate that the expandable structure224 may include other elements that may be collapsed and/or expanded.For example, in an alternative embodiment, the expandable structure mayinclude an inflatable balloon (not shown) carrying a plurality oftransducer elements. As the balloon is inflated, the transducer elementsmay assume a configuration of a transducer array, similar to theprevious embodiment. In a further alternative embodiment, the structure204 may include other hinged elements that are connected to otherwisecarried by the distal end 223 of the elongate member 220.

As shown in FIG. 8, the expandable structure 224 is expanded towards theenlarged configuration within a balloon 251. The transducer device 200also may include a tubular element 250, including a proximal end 252, adistal end 254, and a lumen 256 extending between the proximal anddistal ends 252, 254. The tubular element 250 may be positioned withinthe lumen 214 of the delivery device 202, and surround the elongatemember 220.

The balloon 251 may be coupled to the distal end 254 of the tubularelement 250 such that an interior 258 of the balloon 251 communicateswith the lumen 256 of the tubular element 250. The balloon 251 isexpandable, similar to the previous embodiment, towards an expandedconfiguration that is larger than the expandable structure 224 in itsenlarged configuration, e.g., to substantially engage a wall of a bodypassage within which the transducer device 200 is introduced. Theballoon 251 may a collapsed configuration or low profile when deflatedand disposed within the lumen 214 of the delivery device 202, and may beinflated towards the expanded configuration. The balloon 251 ispreferably made from a material including an acoustic impedance that issubstantially similar to the acoustic impedance of body tissue, asdiscussed previously with reference to the balloon 150.

When using the ultrasound device 200 to treat a prostate, the tubulardelivery device 202 is first inserted into a rectum through a rectalorifice (not shown). The expandable structure 224 may be placed withinthe lumen 214 of the delivery device 202 before or after the tubulardelivery device 202 is inserted into the rectum. If the transducerdevice 200 includes a balloon 251, the balloon 251, together with theelongate member 220, may be introduced into the lumen 214 of thedelivery device 202 before or after the delivery device 202 is insertedinto the rectum.

After the distal end 212 of the delivery device 202 has been advancedsufficiently, the distal end of the elongate member 220 may be advancedfrom the delivery device to deploy the expandable structure 224 withinthe rectum. The expandable structure 204 may be manipulated within therectum until the petals 225 are fully exposed, whereupon the petals 225may automatically expand or may be actuated to expand towards theenlarged configuration. In the enlarged configuration, the transducerelements 206 generally assume a transducer array 226, which may then beoriented towards a target tissue region (not shown).

If the transducer device 200 includes a balloon 251, the balloon 251maybe advanced into the rectum before or simultaneously with theelongate member 220. Other methods known in the art may also be used todeploy the balloon 251. For example, a plunger or guidewire (not shown)may be used to deliver the balloon 251 into the rectum.

After the balloon 251 and the expandable structure 204 have beendeployed and desirably placed within the rectum, fluid may be deliveredinto the interior 258 of the balloon 251 to expand the balloon 251 untilit substantially engages the surrounding wall of the rectum. Fluid maybe delivered directly into the open proximal end 252 of the tubularelement 250 and into the interior 258 of the balloon 251. Alternatively,a coupler or plug (not shown), similar to that described previously withreference to FIG. 5, may be used to seal the balloon 251 and/or couplethe balloon 251 to a source of fluid.

Once the transducer array 226 is properly positioned and/or oriented,drive signals may be delivered to the transducer elements 206 to focusacoustic energy to the target site, similar to the previous embodiment.After sufficient ultrasonic energy has been delivered, the expandablestructure 224 (and balloon 251) may be collapsed, repositioned, expandedand activated to focus acoustic energy at a an other target site. Oncesufficient tissue is treated, the expandable structure 224 (and balloon251) may be withdrawn into the lumen 214 of the delivery device 202and/or otherwise removed from the rectum.

Although the above described embodiments have been described withreference to treating a prostate, it should be understood by thoseskilled in the art that the apparatus and methods described herein mayalso be used to treat other areas of a body. In addition, the transducerdevices described herein may be used in cooperation with externaltransducer arrays, such as those described in the referencesincorporated by reference elsewhere herein. Thus, a hybrid procedure, inwhich acoustic energy is delivered to a target site using twotransducers, one internal and one external, simultaneously.Alternatively, multiple transducer devices, such as those describedherein, may be inserted into different body passages for deliveringacoustic energy to a target site in cooperation within one another. Forexample, in a single treatment, a first transducer device may beintroduced into a rectum, and a second transducer device may beintroduced into a vagina of a female patient to treat tissue adjacentthe rectum and the vagina. Furthermore, besides treating tissue, thetransducer devices described herein may also be for obtaining acousticimages of tissue regions within a patient.

Thus, although several preferred embodiments have been shown anddescribed, it would be apparent to those skilled in the art that manychanges and modifications may be made thereunto without departing fromthe scope of the invention, which is defined by the following claims andtheir equivalents.

1. An apparatus for delivering acoustic energy to a target site adjacenta body passage, comprising: a first member comprising a proximal end, adistal end having a size and shape for insertion into a body passage,and a first transducer carried on the distal end; and a second membercomprising a proximal end, a distal having a size and shape forinsertion into the body passage, and a second transducer carried on thedistal end, the first and second transducers detachably coupled to eachother to at least partially form a transducer array for deliveringacoustic energy to a target site adjacent the body passage.